Method of preparing ores for use in the manufacture of steel.



No. 887,379. PATENTED MAY 12,1908.

E. B. CLARK. METHOD OF PREPARING ORES FOR USE IN THE MANUFACTURE OFSTEEL.

APPLICATION FILED NOV. 11. 1907.

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No. 887,379. PATENTED MAY 12, 1908. E. B. CLARK.

METHOD OF PREPARING ORES FOR USE IN THE MANUFACTURE OF STEEL.

APPLICATION FILED NOV. 11. 1907.

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UNITED STATES PATENT OFFICE.

' EUGENE B. CLARK, OF CHICAGO, ILLINOIS, ASSIGNOR TO AMERICAN SINTERINGCOMPANY,

OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

METHOD OF PREPARING ORES FOR USE IN THE MANUFACTURE OF STEEL.

Specification of Letters Patent.

Patented May 12, 1908.

Application filed November 11, 1907. Serial No. 401,713.

To all whom itma-y concern:

Be it known that I, EUGENE B. CLARK, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and Improved Method of Preparing Ores for Use" inthe Manufacture of Steel, of which the following is a specification,reference being had to the accom anying drawings.

My invention relates to the treatment of ores for the purpose ofpreparing them for use in the manufacture of steel by the opt-nphosphorus steel is so great. As a matter of As is well known to thosefamiliar with the hearth process.

art, the bulk of the steel manufactured is made by one of twoprocesses,to-wit, the

' Bessemer rocess and the open hearth process. The essemer processconsists in blowing air through a bath of molten iron with a view tooxidizing the impurities contained in the pig-iron. This oxidationproduces the heat necessary without the burning of additional fuel.There are really two Bessemer rocesses, that known as the acid and thatnown as the basic. In the acid process, it is not possible to removephosphorus from the iron, and, inasmuch as practically all thephosphorus contained in the iron, the coke and the limestone used in themanufacture of pi -iron must appear in the pig-iron, the phosp oruscontained in the raw materials appear also in the steel. Since a hi hpercenta e of phosphorus in the steel is OI)- jectionabie for manypurposes, it is necessary when manufacturing steel by the acid rocess toutilize iron der1ved from so-called essemer ores,that is, ores having acomaratively small percentage of phosphorus. n the basic rocess, it ispossible to remove phosphorus, ut in order to utilize the basic essemerrocess satisfactorily, it is necessary that tie pig-iron, and thereforethe ore of which the pig-iron is made, shall contain a comparativelyhigh percentage of phosphorus. Therefore, ore containing too muchphosphorus for the acid Bessemer process and too ittle phosphorus forthe basic Bessemer process must be manufactured into steel by some otherprocess, as, for example, the open hearth process. Open hearth steelalso may be manufactured by either the acid process or the basicprocess, and it is also true that in the acid open hearth processhosphorus cannot be removed, but it can lie satisfacmt, a large andincreasing proportion of the available ore supply falls into thecategory of ores which must be converted into steel through the mediumof the basic open hearth process. This explains the wellrecognized factthat the open hearth process, and especially the basic open hearthprooess,has increased in importance to a remarkable extent, and isdestined to increase still more in the future.

In the operation of the open hearth process, it is necessary to useore,-that is, iron oxid,in order to sup )ly the necessary amount ofoxygen to the i) in the furnace. This ore should have certain qualities.In the first place, itshould be in lumps, so that it can be thrown intothe bath and will immediately pass through the slag floating on the topthereof and so reach the metal underneath. The ore should be low insilica in order that it may not increase the necessary slag volume, orattack the lining of the furnace. Ore of this character has always beendifficult to obtain, and the very greatly increased demand has made theprocuring of desirable ore a matter of great difficulty, as it is alsoof great importance. Where a large percentage of molten pi -iron is usedin the manufacture of the steel; it is customary to put fine ore intothe furnace before pouring in the molten pig-iron. Under theseconditions, the reaction between the ore and the pig-iron is delayed,and when it takes place, is extremely violent, nearly always causingslag and metal to boil out of the door of the furnace and sometimescausing violent explosions that result in destroying the roof of thefurnace and also in doing great damage and endangering life in the steelplant.

The supply of fine ores having the proper ath of molten ironchemicalcomposition is adequate, but heretofore it has not beenpracticable to use them generally owing to the objection above noted.The object of my invention is to provide a new" and improved method oftreating such fine ores so that they may be satisfaca pIasticconditioninto blocks or masses of asize suited to the open hearth requirements.

I have discovered that this material, when compressed into blocks ormasses, will stick together solidly and will be of the physicalcharacter required for ore to be used in the open hearth process. Myimproved process may be employed in the treatment of fluedust, pyritesresidue, or other materials which now are not at all used in the openhearth process,that is to say, it is not necessary that fine ores beused for the manufao ture of these open hearth blocks or lumps,

but either fine ore or suitable waste products,

or a mixture of fine ore and suitable waste products may be employed.

In the drawings I have shown one form of apparatus which may beconveniently employed for carrying out my improved method, the apparatusshown bein in part similar to the apparatus for sintering e oresillustrated and described in atent to 'J. G. Bergquist, No. 853,433,dated May 13, 1907. It W'Lll be understood, however, that any othersuitable form of ap aratus may be employed.

In the awings:Figure 1 is a side elevation of a rotary kiln, with thecompressing mechanism, some parts being in section; Fig. 2 is ahorizontal section on line 22 of Fig. 1; nd Fig. 3 is a vertical sectionon line 33 of Iteferring to the drawings, 4 indicates a rotary kiln inthe form of a hollow cylinder suitably lined with refractory material.Said kiln is mounted on rollers 5 so that it may rotate freely and isprovided with a gear 6 which meshes with a pinion 7 driven from anysuitable source of ower, as, for example, the pulley 8 which is iven byabelt. The kiln 4 is rotated slowly while in operation and in generaloperates in the manner described in, said Berg uist patent. The kiln 4is inclined slightly from its inlet to its outlet end so that thematerial entering at one end gradually moves downward and is dischargedat the lower end. For the purpose ried by the rolls 2223.

of scraping the material from the inner surface of the kiln, an endlesschain 9 is provided which is equipped with scrapers 10 placed atintervals so t the kilnmoving in the same'direction as the materialtherein, it scrapes the inner surface of the kiln and promotes thepassage of the material therethrough. The chain 9 is supported bysuitable ulleys 1l12.1314, all or a part of whic are driven by anysuitable means. In the drawings, I have illustrated the pulley 13 asbeing provided with a pulley 15 by which it is driven. 16 indicates awater bath through which that ortion of the chain lying outside of the npasses for cooling purposes. "17 indicates the base portion of a stackor chimney which connects with the upper or inlet end of the kiln, and18 indicates a feed chute which discharges the materials to be treatedinto the upper end of the kiln. 19 indicates a chambered closure whichconnects with the delivery end of the kiln, being mounted on wheels 20so that it may readily be moved toward and from the kiln. All theseparts are illustrated and described in the Bergquist patent hereinbeforementioned, and, separately considered form no part of my inven.

tion.

21 indicates a hopper located below the delivery endof the kiln intowhich the at as the chain travels through materials passing through thekiln are discharged.

2223 indicate rolls located under the discharge 0 ening of the ho per21, as best shown in ig. 3. Said ro s are provided with pockets orrecesses 24 at intervals in their peripheries, the pockets of one. rollbeing staggered with reference to those of the other, and the rolls areso arranged as to cooperate to compress in said ocketsthe materialpassing through the opper 21. To this end, the rolls are placed in suchposition that the material falling through the hopper is deposited onthe peripheries of the rolls and enters the pockets of one roll or theother and is compressed by the periphery of the other roll. The materialso compressed 1n the pockets of the rolls is deposited by the rotationof the rolls in a hopper 25 which underlies the rolls, as shown in Fig.3, and preferably is discharged from the hopper 25 into a skip 26 bywhich it may be hoisted to any suitable point. The rolls 22 23 aredriven in any suitable way, preferably by means of a belt 27 working ona pulley 28 which drives suitable intermeshing gears carbe used in theopen hearth process, so that the flue-dust or other material treated isconverted physically into such form that it may be successfully employedin that way.

While I prefer to make the pockets in the compressing rollsbrick-shaped, they may be of any other suitable shape.

I am aware that it has heretofore been proposed to convert granular orpulverulent ores into lumps by intimately mixing therewith molten slag,or other binding agent, but such process differs radically from mine inthat the masses thereby formed are not homogeneous and are held togethersolely by means of the binding agent. I am also aware that it has beenproposed to form fine ores into masses by dropping the fine ore throughan open furnace chamber upon roll- ,ers which act to compress thepowdered ore while in a partly fused condition. This process alsodifiers from mine in that the ores are not first agglomerated into smallhomogeneous masses which are afterwards compressed into larger lumps.Neither of the two methods referred to nor the products thereby producedare herein claime What I claim as my invention and desire to secure byLetters Patent is 1-- 1. The method of treating fine ores for thepurpose described, which consists in first agglomerating the ore intosmall substantially homogeneous lumps and then'compressing theagglomerated ore into larger lumps or blocks.

2. The method of treating fine ores for the purpose described, whichconsists in passing the ore through a substantially horizontalcylindrical kiln wherein it is reduced to a semiplastic condition byheat the kiln being meanwhile rotated to agglomerate the ore into smallhomogeneous lumps, and then compressing such lumps into larger lumps orblocks. I

3. The product composed of a number of small homogeneous lumps ofagglomerated ore compressed together while in a semiplastic condition.

. EUGENE B. CLARK.

Witnesses:

ALBERT H. ADAMS, WILLIAM H. DE BUSK.

